docs(cli): overhaul help and version output with color and structure

Rewrite `print_help` to use the full color palette and group options into
labeled sections (Encoding, Input, Savings log, Output, General, and a
new Configuration files section). The Configuration files section
documents the preset directory and skip.conf path, including the
variables available to preset authors and the security note about
trusted sources.

Default values for `--preset`, `--nice`, and `--saving-file` are now shown
inline using `$PRESET_NAME`, `$NICE_VALUE`, and `$SAVING_FILE` rather than
being hardcoded, so they always reflect the actual defaults.

Rewrite `print_version` to inline the BSD-3-Clause license text directly
instead of conditionally catting `LICENSES/BSD-3-Clause.txt`. This makes
`--version` self-contained regardless of where the script is invoked from.

Apply the same color treatment to the short usage hint printed when no
arguments are given.

1 files changed, 84 insertions, 31 deletions

diff --git a/transcode.sh b/transcode.sh
index 33803e7..61ecc5e 100755
--- a/transcode.sh
+++ b/transcode.sh
@@ -190,36 +190,64 @@ debug() {
 }
 
 print_help() {
-  printf "%s - %s - %s
+  printf "${BOLD}${MAGENTA}%s${ALL_OFF} - ${BOLD}${CYAN}%s${ALL_OFF} - ${BOLD}%s${ALL_OFF}
 
-Usage: %s [OPTION] [--] FILE...
+${BOLD}${BLUE}Usage:${ALL_OFF} ${BOLD}${MAGENTA}%s${ALL_OFF} ${BOLD}${YELLOW}[OPTION]... [--]${ALL_OFF} ${BOLD}${GREEN}FILE...${ALL_OFF}
 
-Options:
-  -c, --continue          Continue with next file even if ffmpeg fails
-  -f, --encodefile PATH   File containing list of files to encode
-  --encodefile=PATH
-  -n, --dry-run           Show what would be done, don't run ffmpeg
-  -N, --nice VALUE        Nice value for ffmpeg (default: 19)
-  --nice=VALUE
-  -s, --saving            Log filesize savings (filename, orig, new, %%)
-  --saving-file PATH      Specify where to save filesize savings (default: transcode_savings)
-  --saving-file=PATH
-  -S, --skip-codec LIST   Add codecs to skip (comma/space/colon separated)
-  --skip-codec=LIST
-  -l, --only-if-smaller   Only overwrite files if the transcoded file is smaller
-  -p, --preset NAME       Load ffmpeg arguments from a preset (default: default)
-  --preset=NAME
-  -h, --help, -?          Show this help text and exit
-  -q, --quiet             Do not output anything, takes precedence over -v and --verbose
-  -v, --verbose           Be more verbose
-  --version               Print script information and version
-  --color                 Force colored output
-  --no-color              Disable colored output
+Long options that take a value also accept ${BOLD}${YELLOW}--option${ALL_OFF}${BOLD}${CYAN}=${ALL_OFF}${BOLD}${GREEN}VALUE${ALL_OFF} syntax.
 
-Examples:
+${BOLD}${BLUE}Encoding options:${ALL_OFF}
+  ${BOLD}${YELLOW}-p, --preset${ALL_OFF} ${BOLD}${GREEN}NAME${ALL_OFF}           load ffmpeg arguments from a preset (default: ${BOLD}${RED}%s${ALL_OFF})
+  ${BOLD}${YELLOW}-N, --nice${ALL_OFF} ${BOLD}${GREEN}VALUE${ALL_OFF}            nice value for ffmpeg (default: ${BOLD}${RED}%d${ALL_OFF})
+  ${BOLD}${YELLOW}-n, --dry-run${ALL_OFF}               show what would be done, do not run ffmpeg
+  ${BOLD}${YELLOW}-l, --only-if-smaller${ALL_OFF}       only replace original if new file is smaller
+  ${BOLD}${YELLOW}-c, --continue${ALL_OFF}              continue with the next file even if ffmpeg fails
+
+${BOLD}${BLUE}Input options:${ALL_OFF}
+  ${BOLD}${YELLOW}-f, --encodefile${ALL_OFF} ${BOLD}${GREEN}FILE${ALL_OFF}       file containing a list of files to encode
+  ${BOLD}${YELLOW}-S, --skip-codec${ALL_OFF} ${BOLD}${GREEN}LIST${ALL_OFF}       skip files with these codecs;
+                              ${BOLD}${GREEN}LIST${ALL_OFF} is comma, space, or colon separated
+
+${BOLD}${BLUE}Savings log options:${ALL_OFF}
+  ${BOLD}${YELLOW}-s, --saving${ALL_OFF}                log filesize savings to a TSV file
+      ${BOLD}${YELLOW}--saving-file${ALL_OFF} ${BOLD}${GREEN}FILE${ALL_OFF}      path for the savings log (default: ${BOLD}${RED}%s${ALL_OFF})
+
+${BOLD}${BLUE}Output options:${ALL_OFF}
+  ${BOLD}${YELLOW}-q, --quiet${ALL_OFF}                 suppress all output; takes precedence over ${BOLD}${YELLOW}-v${ALL_OFF}
+  ${BOLD}${YELLOW}-v, --verbose${ALL_OFF}               explain what is being done
+      ${BOLD}${YELLOW}--color${ALL_OFF}                 force colored output
+      ${BOLD}${YELLOW}--no-color${ALL_OFF}              disable colored output
+
+${BOLD}${BLUE}General options:${ALL_OFF}
+  ${BOLD}${YELLOW}-h, --help${ALL_OFF}                  display this help and exit
+      ${BOLD}${YELLOW}--version${ALL_OFF}               output version information and exit
+
+${BOLD}${BLUE}Configuration files:${ALL_OFF}
+  ${BOLD}${CYAN}%s/<NAME>.sh${ALL_OFF}
+                              preset file; must define a bash array ${BOLD}${GREEN}ffargs${ALL_OFF} with
+                              the ffmpeg encoding arguments. the following
+                              variables are available to presets:
+                                ${BOLD}${GREEN}input_codec${ALL_OFF}          e.g. h264, hevc
+                                ${BOLD}${GREEN}input_pixel_format${ALL_OFF}   e.g. yuv420p
+                                ${BOLD}${GREEN}output_pixel_format${ALL_OFF}  derived from input
+                              presets are sourced as shell code; only use
+                              trusted presets from trusted directories.
+
+  ${BOLD}${CYAN}%s${ALL_OFF}
+                              skip file; one codec name per line, lines
+                              starting with ${BOLD}${YELLOW}#${ALL_OFF} are treated as comments.
+                              codecs listed here are skipped in addition to
+                              any codecs passed via ${BOLD}${YELLOW}--skip-codec${ALL_OFF}.
+
+${BOLD}${BLUE}Examples:${ALL_OFF}
   %s video.mp4
   %s -s -f list.txt
-  %s -n -N 10 my_movie.mkv\n" "$SCRIPTNAME" "$VERSION" "$DESCRIPTION" "$SCRIPTNAME" "$SCRIPTNAME" "$SCRIPTNAME" "$SCRIPTNAME"
+  %s -n -N 10 my_movie.mkv\n" \
+    "$SCRIPTNAME" "$VERSION" "$DESCRIPTION" \
+    "$SCRIPTNAME" \
+    "$PRESET_NAME" "$NICE_VALUE" "$SAVING_FILE" \
+    "$PRESET_DIR" "$SKIP_CODECS_FILE" \
+    "$SCRIPTNAME" "$SCRIPTNAME" "$SCRIPTNAME"
 }
 
 print_version() {
@@ -229,12 +257,36 @@ ${YELLOW}${BOLD}Description:${ALL_OFF} %s
 ${BLUE}${BOLD}Author:${ALL_OFF} %s
 ${MAGENTA}${BOLD}Date of creation:${ALL_OFF} %s
 ${CYAN}${BOLD}Date of revision:${ALL_OFF} %s
-${RED}${BOLD}License:${ALL_OFF} %s\n" "$SCRIPTNAME" "$VERSION" "$DESCRIPTION" "$AUTHOR" "$DATE_OF_CREATION" "$DATE_OF_REVISION" "$LICENSE"
+${RED}${BOLD}License:${ALL_OFF} %s
 
-  if [[ -f "LICENSES/${LICENSE}.txt" ]]; then
-    printf "\n"
-    cat "LICENSES/${LICENSE}.txt"
-  fi
+Copyright (c) 2025 Dennis Fink <dennis.fink@c3l.lu>.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice,
+this list of conditions and the following disclaimer in the documentation
+and/or other materials provided with the distribution.
+
+3. Neither the name of the copyright holder nor the names of its contributors
+may be used to endorse or promote products derived from this software without
+specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS \"AS IS\" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.\n" \
+    "$SCRIPTNAME" "$VERSION" "$DESCRIPTION" "$AUTHOR" "$DATE_OF_CREATION" \
+    "$DATE_OF_REVISION" "$LICENSE"
 }
 
 filesize() {
@@ -407,7 +459,8 @@ load_preset() {
 
 if [[ $# -eq 0 ]]; then
   debug "No parameters were specified"
-  printf "Usage: %s [OPTION] [--] FILE...\nRun '%s --help' for full usage information.\n" "$SCRIPTNAME" "$SCRIPTNAME" >&2
+  printf "${BOLD}${BLUE}Usage:${ALL_OFF} ${BOLD}${MAGENTA}%s${ALL_OFF} ${BOLD}${YELLOW}[OPTION] [--]${ALL_OFF} ${BOLD}${GREEN}FILE...${ALL_OFF}
+Run ${BOLD}${MAGENTA}%s${ALL_OFF} ${BOLD}${YELLOW}--help${ALL_OFF} for full usage information.\n" "$SCRIPTNAME" "$SCRIPTNAME" >&2
   exit $EXIT_USAGE_ERROR
 fi